I started the c25k today. My upper thighs are burning. I have never been a runner/jogger/or any other type of exercise type person. I have smoked sonce i was 19. I am 33 now. I have been getting these strange urges to run. I want to be fot now and o need this sort of thing to quit the bad habit. i can't wait to see the results of being in shape and being able to quit.